An adversary proceeding is a lawsuit related to a particular bankruptcy case. An adversary proceeding begins when a complaint is filed with the court and the appropriate fee is paid. This complaint is given a separate case number, and advances according to the court's policies. More information on adversary proceedings may be found in the Bankruptcy Code, the Federal Rules of Bankruptcy Procedure, and the court's local rules.

Adversary proceedings are extremely complex; parties not represented by an attorney are strongly urged to consult a bankruptcy attorney when considering filing an adversary proceeding.